battery AUDI A4 1998 B5 / 1.G AWM Engine Oxygen Sensor Control Checking Workshop Manual

24-91
If specified value is obtained:

- Check voltage supply of oxygen sensor
heating.

Checking voltage supply for oxygen sensor
heating

Note:
When the Engine Control Module (ECM) switches oxygen sensor heating
on and off, it may be observed via the function "read measuring value
block", in display group number 041 display field 2.
If there is no voltage: - Connect multimeter between terminal 3 and 4 for voltage
measurement.
- Start engine.

Specification: approx. battery voltage

- Connect multimeter for voltage measurement as follows.Harness connector
Terminal
Measure to
3 (B+) Vehicle Ground (GND)
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24-92

- Operate starter briefly.


Specification: approx. battery voltage
If there is no voltage again:

- Check wire connection from terminal 3 of
connector to Fuel Pump (FP) relay via fuse for
open circuit:

Electrical Wiring Diagrams, Troubleshooting &
Component Locations
If voltage supply is OK:

Note: - Connect multimeter for voltage measurement as follows:Harness connector
Terminal
Measure
to
4 (Ground -GND- activation of Engine Control Module -
ECM-) B+
- Start engine.

Specification: approx. battery voltage
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24-109
If specified value is obtained:

- Check voltage supply of oxygen sensor
heating.

Checking voltage supply for oxygen sensor
heating

Note:
When the Engine Control Module (ECM) switches oxygen sensor heating
on and off, it may be observed via the function "read measuring value
block", in display group number 041 display field 4.
If there is no voltage: - Connect multimeter between terminal 1 (B+) and 2 (Ground -GND-) for
voltage measurement.
- Start engine.

Specification: approx. battery voltage

- Connect multimeter for voltage measurement as follows:Harness connector
Terminal
Measure to
1 (B+) Vehicle Ground (GND)
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24-110

- Operate starter briefly.


Specification: approx. battery voltage
If there is no voltage again:

- Check wire connection from terminal 1 of
connector to Fuel Pump (FP) relay via fuse for
open circuit:

Electrical Wiring Diagrams, Troubleshooting &
Component Locations
If voltage supply is OK:

- Connect multimeter for voltage measurement as follows:Harness connector
Terminal
Measure
to
2 (Ground -GND- activation of Engine Control Module -
ECM-) B+
- Start engine.

Specification: approx. battery voltage, possibly fluctuating
- Switch ignition off.
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